March 15, 1999|By Carl Schoettler | Carl Schoettler,SUN STAFF
Archivists and conservationists worry that the alkaline crystals could react with the acid of the ink and that as the documents are raised and lowered each day there could be abrasion from the crystals. Crystallization and "grizzling," the formation of surface scratches, This line is longer than measure/can't be broken could eventually become a "cosmetic issue." You might be looking at the Charters of Freedom through a glass fog.
High-tech materials
All these issues and a lot more have been addressed by a core team of about a dozen and a half experts in everything from inert papers to the coefficient of thermal expansion of glass and metals. NASA and the National Institute of Standards and Technology have contributed expertise. Outside preservationists and analysts swell the number involved in designing the new encasements to 50 or 60.
In the model being tested now, the charters will lie on a bed of inert paper -- manufactured by NIST, as the paper in the present encasements was made by their predecessor the old Bureau of Standards -- resting on a perforated platform of aircraft-grade aluminum.
They'll be covered by three layers of tempered, heat-soaked, glare-resistant glass. The frame will be cut from a single block of pure titanium. The titanium frame will be bolted to the aluminum base, so they can be opened without destroying the frame -- something that will happen when the present display cases are opened.
The aluminum base will be plated with highly polished nickel to create a "diffusion path" seal where it comes in contact with the glass. A ring of spring-like Incobel metal plated with gold or lead will provide the final seal.
The new frame will be tested with helium, which has a very small molecule that can "migrate" through glass. But when the charters are finally re-encased, the air inside will be replaced with argon, a gas with a much bigger molecule that will presumably stay put.
Among all the experts there's a pervasive sense of dealing with some of the country's "most precious documents."
No one, of course, will know everything about the precise state of the charters until the present encasements are opened.
"There's a lot of excitement about this project," says Rick Judson, the project manager for the Archives. "But there's a little apprehension too. For one thing nobody's touched these documents in almost 50 years. The other thing is you really don't get a second chance to make a good first impression. You can't fail."
You don't want to drop the Declaration of Independence, so to speak.
"We're trying to be extremely familiar [with the condition of the documents]," Nicholson says. "When we get ready to carry out the change, we'll be very well prepared. We don't want to be surprised. We want to be totally prepared for what's going on."
This, after all, is one Constitutional question that can't be appealed to the Supreme Court.
Pub Date: 3/15/99
